Carburetor anti-icing device



CARBURETOR ANTI I C ING DEVICE Filed March 1, 1943 2 Sheets-Sheet l@Earnay I April 9, 1946.; s. E. HEYMANN CARBURETOR ANTI-ICING DEVICEFiled March 1, 1945 2 Sheets-Sheet 2 dillwev/j c rw' 44/10 101 IPatented Apr. 9, 1946 UNITED STATES PATENT OFFICE CARBURETOR ANTI-ICINGDEVICE Seymour E. Heymann, Chicago, 111., assignor. to Stewart-WarnerCorporation, Chicago, 111., a corporation of Virginia Application March1, 1943, Serial No. 477,524

6 Claims.

My invention relates to carburetor anti-icing devices, and is moreparticularly concerned with an anti-icing device for the carburetors ofaircraft engines.

In aircraft operation the temperature of the atmospheric air variesgreatly with different altitudes and different weather conditions, andgreat difllculty is encountered with the formation of ice in thecarburetor of the aircraft engine. While various meanshave been proposedto overcome these difliculties, none of the solutions heretoforeproposed are entirely satisfactory.

An object of my invention is to provide an antiicing device for aircraftcarburetors which will operate satisfactorily under the most severeconditions, which is simple, inexpensive, light in weight and easy toinstall.

Another object of my invention is to provide an anti-icing device foraircraft carburetors which requires no additional operation on the partof the pilot of the aircraft.

Another object of my invention is to provide a carburetor anti-icingdevice which may use fuel from the main fuel supply for the aircraftengine or which may have its own source of fuel upp y.

Another object of my invention is to provide a carburetor anti-icingdevice which consumes no additional fuel or electricity when not in use.

Another object of my invention is to provide a carburetor anti-icingdevice which utilizes an internal combustion heater for supplying theheat necessary to prevent the formation of ice in the carburetor.

Other objects and advantages will become apparent as the descriptionproceeds.

In the drawings:

Fig. 1 is a partial sectional view through the cowling of a conventionalaircraft engine installation showing my invention applied thereto;

Fig. 2 is the partial vertical section taken'on the line 2-2 in Fig. 1;

Fig. 3 is a sectional view through the burner forming a part of myinvention; and

Fig. 4 is a wiring diagram.

In Fig. 1, I have illustrated a typical installation of a radial aircooled engine It for aircraft. The engine Ill is enclosed in a cowlingl2, and the air supply for the engine carburetor normally enters aninlet l4 located outside of the cowling 12. The inlet l4 connects with apipe l6 leading to the engine carburetor i8 which forms a combustiblemixture delivered by the carburetor to the inlet 20 of the enginesupercharger.

The supercharger 20 has a circular blower case 22 which is connected byintake manifolds 24 to the individual engine cylinders, such as thecylinder 26 shown in Fig. 1. Each cylinder is provided with an exhaustpipe 28 which projects through the cowling l4 and discharges the exhaustgases directly to atmosphere or into any suitable exhaust manifold.

The carburetor l8 may be of any suitable or common type and receives asupply of fuel from a float bowl 30 connected by a pipe 32 to the enginefuel tank. A thermometer bulb 34 projects into the pipe l6 and isconnected to a suitable indicator on the instrument board of theaircraft to indicate to the pilot the temperature of the air flowing tothe carburetor l8. A nozzle 36 is located in the pipe I6 and isconnected by tube 38 to a hand operated force pump for forcing alcoholin a spray form into the pipe IE to dissolve any ice which has formed inthe engine carburetor. The thermometer 34 and nozzle 36 are conventionalequipment and form no ,part of my invention. It is only feasible tospray alcohol into the carburetor inlet pipe H5 at infrequent intervals,and the provision of equip- .ment for so doing does not constitute asatisfactory solution of the icing problem. While I have shown the inletpipe for the carburetor as being equipped with the alcohol nozzle 36,this nozzle is not necessary in installations using my invention.

The carburetor inlet pipe I 6 is provided with an opening 4|! in theforward wall thereof, and this opening is normally closed by a shutter42. The shutter 42 is pivoted at 44 and has an arm 46 connected to a rod48 extending into the pilot's compartment. When the thermometer 34indicates that the air entering the inlet I4 is within a giventemperature range, the pilot shifts the shutter 42 to the position shownin Fig. 1 This prevents any air from reaching the carburetor by way ofthe inlet l4, and permits air from the inside of the engine cowling i 2to flow to the carburetor by way of opening 40 and pipe l6. While theair entering the open end 50 of the cowling I2 is heated somewhat as itpasses over the engine in, the heat which this air receives from theengine is insuflicient under some conditions to raise the temperature ofthe air flow-"- ing to the carburetor enough to prevent the formation ofice in this carburetor. I therefore provide additional means forincreasing the temperature of the air and reaching the carburetor by wayof opening 40 in the pipe l6.

This additional means is in the form of an intemal combustion heaterindicated generally by reference character 52. The heater 52 has 9.cylindrical casing 54 into which air is forced by a blower 56 which ispreferably operated from a small electric motor but which may be drivenin any other suitable manner. While I have shown my heater as beingsupplied with air by a blower, a ram or any other suitable source of airsupply could be utilized.

A Venturi tube 58 is located in the casing 54 and delivers a combustiblemixture to a combustion chamber 60 through a burner tube 82. A fuel jet84 is located in the restricted throat of the Venturi tube 58 andsupplies fuel thereto from a float bowl 66. The up er part of the floatbowl is connected by a pi e 68 to a ram 18 in the path of air dischargeby the blower 58 so that the d fference in pressure between the ram 78and throat of the Venturi tube 58 is available to cause fuel to flowfrom the float bowl 86 to the Jet 84 and pass through the o enings ofthis jet to the interior of the Venturi tube. V

The combust ble mixture entering the combustion chamber 60 by way of theburner tube 82 is i nited by an electrical igniter 72. On y part of theair discharged bv the blower 56 enters the Venturi tube 58 to form thecombustible mixture burned in the combustion chamber 68. The r mainderoi the air dischar ed by the blower 58 flows around the combustionchamber 68 and mixes with the hot products of combustion dischar ed fromthe open rigbthand end of th s combustion cha ber. The heated was andair from the burner 52 pa ses thr u h a flexible hose ll to the dischare nozzle 16 located immediately in front of the opening In i thecarburetor air inlet pipe l6. When the shutter 42 is in the positionshown in Fig. 1, the hot mixture of air and burned gases dischar ed bvthe nozz e 18 flows into pipe i6 along with addi ional air from theinterior of the cowling i 2. Such additional air has received some heatfrom the engine l and the additional heat supplied by the burner 52raises the temperature, of the air fiOWlng to the carburetor i 8sufllciently to prevent the formation of ice therein under all o eratinconditions.

In the embodiment shown in the drawings. the heater 52 is automatical yset in operation whenever the shutter 42 is shifted to the positionshown in Fig. l. The heater remains in operation as long as the shutterremains in this position unless a manual switch is operated todisconnect the electrical control circuit from its source of electricalenergy. When the shutter 42 is shifted to close the opening 40. theheater is automatically cut out.

The foregoing automatic operation is effected by means of a switch 18having a fixed contact 88 and a movable contact 82 mounted on an arm 88.The arm 84 is biased so that it normally tends to move the contact 82out of engagement with the contact 80. A s ring 86 projects into thepath of the shutter 42, and when the shutter is moved to the positionshown in Fig. l, the upper end of the spring 86 is flexed to the rightso that the projection 88 carried by the central portion of this springforces movable contact 82 into engagement with contact 88. 1A5 soon asthe shutter 42 is moved to a position closing opening 48, the upper endsof spring 86 and switch arm 84 move to the left, thereby breaking thecircuit through the switch 18.

In the wiring diagram of Fig. 4, the motor for driving the blower isindicated by the letter M.

the solenoid valve 88 which controls the flow of fuel through pipe 92which connects float bowl 88 with the fuel tank for the engine Ill orwith any other suitable source of fuel supply. This solenoid valve isbiased toward closed position and is open only as long as the solenoidis electrically energized. A manual switch 93 is preferably provided inthe circuit connecting the igniter, blower motor and solenoid valve witha suitable source of electrical energy, such, for example, as thebattery 94. A fuse 86 or other overload device is also preferablylocated in this circuit. The manual switch 93 is normally closed whenthe aircraft is in operation, and the heater 52 is automaticallygontgolled by the shifting movements of the shut- 1 er From theforegoing it will be apparent that I have provided an exceedinglysimple, inexpensive, compact and efficient anti-icing device foraircraft carburetors, and that the control of this device requires noadditional attention or operation on the part of the aircraft pilot. Thestarting and stopping of the burner of the anti-icing device isautomatically controlled by the shifting of a shutter which is a part ofthe standard equipment of the aircraft and forms one of the usualcontrols therefor. My anti-icing device can be mounted in space which isnot used for any other purpose, and can be easily and quickly installedupon existing aircraft.

While I have illustrated only one form of my invention, it is to beunderstood that my in vention is not limited to the details shown anddescribed but may assume numerous other forms. and that the scope of myinvention is defined by the following claims.

I claim:

1. An anti-icing device for the carburetor of an aircraft engine mountedin a cowlin and having one carburetor air inlet outside of said cowlingand another carburetor air inlet inside of said cowling and a shutterfor controlling admission of air through said inlets, said devicecomprising a burner mounted in said cowling, an electrically operatedblower in said cowling for supplying air to said burner, an electricallyoperated fuel valve' for controlling flow of fuel to said burner, anelectrically operated igniter for said burner, a hose for conducting hotgases from said burner to said inlet located in said cowling, and switchmeans automatically operated by said shutter for controlling saidigniter, fuel valve, and blower.

2. An anti-icing device for the carburetor of an airplane engine mountedin a cowling, said device comprising an inlet pipe for said carburetor,said inlet pipe having one air admission inlet outside of said cowlingand another air admission inlet inside of said cowling, a burner locatedin said cowling, a discharge tube for said burner, a nozzle on the endof said discharge tube, means for supporting said nozzle to dischargeinto the opening located in said cowling, means for varying admission ofair through said openings, and a burner control operated by said lastnamed means for starting and stopping said burner.

3. An aircraft engine installation, comprising an internal combustionengine, a carburetor for said engine, a cowling enclosing said engine, acarburetor air inlet located outside of said cowling, another carburetorair inlet located inside of said cowling, a shutter foicontrollingadmission of air through said inlets, a burner for delivering This motoris in parallel with the igniter I2 and II hot products of combustion toone of said inlets,

means for shifting said shutter, and means operated by said shutter forstarting and stopping said burner.

4. In an arrangement of the type described, the combination of aninternal combustion engine, a carburetor for said engine arranged to therear of the engine so as to receive heat therefrom and having two airinlets, a heater connected with one of said inlets and adaptedindependently of said engine to supply heated gas thereto, means forclosing either of said inlets while leaving the other open, and meansadapted automatically to start said heater into" operation when theinlet connected with the heater is opened. v p

5. In an arrangement of the type described, the combination of aninternal combustion engine, a carburetor for said engine arranged to therear of the engine so as to receive heat therefrom and having two airinlets, means comprising a heater operating independently of said engineand connected with one of said inlets and adapted to deliver heated airand combustion gases thereto,

means for closing either of said inlets while leaving the other open,and means adapted automatically to start said heater into operation whenthe inlet connected with the heater is opened.

6. In an arrangement of the type described, the combination of aninternal combustion engine, a cowling enclosing said engine, acarburetor for said engine arranged inside of said cowling to the rearof the engine so as to receive heat from the engine and having two airinlets, means comprising a' heater operating independently of saidengine and connected with one of said inlets and adapted to deliverheated air and combustion gases to said inlet, means for closing eitherof said inlets while leaving the other open, and means adaptedautomatically to start said heater into operation when the inletconnected with the heater is opened and to throw said heater out ofoperation when said inlet is closed.

SEYMOUR E. HEYMANN.

